643585 has 4 divisors (see below), whose sum is σ = 772308. Its totient is φ = 514864.

The previous prime is 643583. The next prime is 643589. The reversal of 643585 is 585346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 585346 = 2 ⋅292673.

It can be written as a sum of positive squares in 2 ways, for example, as 288369 + 355216 = 537^2 + 596^2 .

It is a cyclic number.

It is not a de Polignac number, because 643585 - 2¹ = 643583 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64354 + ... + 64363.

It is an arithmetic number, because the mean of its divisors is an integer number (193077).

2⁶⁴³⁵⁸⁵ is an apocalyptic number.

It is an amenable number.

643585 is a deficient number, since it is larger than the sum of its proper divisors (128723).

643585 is a wasteful number, since it uses less digits than its factorization.

643585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128722.

The product of its digits is 14400, while the sum is 31.

The square root of 643585 is about 802.2374960073. The cubic root of 643585 is about 86.3379974258.

The spelling of 643585 in words is "six hundred forty-three thousand, five hundred eighty-five".